Semiconductor devices are typically fabricated on a substrate that provides mechanical support for the device and often contributes to the electrical performance of the device as well. Silicon, germanium, gallium arsenide, sapphire and silicon carbide are some of the materials commonly used as substrates for semiconductor devices. Many other materials are also used as substrates. Semiconductor device manufacturing typically involves fabrication of many semiconductor devices on a single substrate.
Substrates are typically formed in the shape of circular wafers having a diameter presently ranging, for example, from less than 1 inch (2.54 cm) to over 12 inches (30.5 cm) depending on the type of material involved. Other shapes such as for example square, rectangular or triangular wafers are possible, however. Semiconductor devices are formed on the wafers by the precise formation of thin layers of semiconductor, insulator and metal materials which are deposited and patterned to form useful semiconductor devices such as diodes, transistors, solar cells and other devices.
Individual semiconductor devices are typically extremely small compared to the size of the wafer on which they are formed. For example, a typical light emitting diode (LED) chip such as the C430-XB290 LED chip manufactured by Cree, Inc., in Durham, N.C. measures only about 290 microns by 290 microns square (1 micron=0.0001 cm). Accordingly, a very large number of LED chips (also referred to as “die”) may be formed on a single 2 inch (5.08 cm) diameter silicon carbide (SiC) wafer. After the die are formed on the wafer, it is necessary to separate at least some of the individual die so that they can be mounted and encapsulated to form individual devices. The process of separating the individual die is sometimes referred to as “dicing” the wafer.
Dicing a wafer into individual semiconductor devices may be accomplished by a number of methods. One method of dicing a wafer involves mounting the wafer on an adhesive surface and sawing the wafer with a circular saw. A series of closely spaced saw cuts is made first in one direction and then in a second direction perpendicular to the first direction. Thereby, a number of individually diced, square or rectangular shaped devices are produced. Other methods of dicing, such as “scribe-and-break” are possible. However, sawing may be preferable for certain applications and substrate types. In particular, for the fabrication of LEDs on silicon carbide substrates, sawing may be preferable.
Sawing may be a slow, laborious task that is typically performed using expensive, complicated saws. Because of the precision required, dicing saws are typically computer-controlled. In addition, the saws typically cut the wafers very slowly to prevent damage to the semiconductor devices. All of these factors tend to make dicing a time-consuming bottleneck in the semiconductor device fabrication process.
Accordingly, there is a need in the art for controlling a semiconductor dicing saw in a manner that may decrease the time required to dice a wafer and/or may improve wafer throughput in the semiconductor device manufacturing process.